Monday, October 16, 2017

[Herpetology • 2017] Scinax onca • A New Species of Scinax (Anura, Hylidae) from the Purus-Madeira interfluve, Brazilian Amazonia

 Scinax onca
Ferrão, Moravec, de Fraga, de Almeida, Kaefer & Lima, 2017 

A new tree frog species of the genus Scinax from the interfluve between the Purus and Madeira rivers, Brazilian Amazonia, is described and illustrated. The new species is diagnosed by medium body size, snout truncate in dorsal view, ulnar and tarsal tubercles absent, nuptial pads poorly developed, skin on dorsum shagreen, dorsum light brown with dark brown spots and markings, white groin with black spots, anterior and posterior surfaces of thighs black, and iris bright orange. The advertisement call consists of a single short note, with 16−18 pulses and dominant frequency at 1572−1594 Hz. Tadpoles are characterized by body ovoid in dorsal view and triangular in lateral view, tail higher than body, oral disc located anteroventrally and laterally emarginated, dorsum of body uniformly grey-brown with dark brown eye-snout stripe in preservative, fins translucent with small to large irregular diffuse dark brown spots.

Keywords: Amazonian rainforest, Amazonas, anuran diversity, Brazil, Rondônia, Scinax onca sp. n.

Figure 5.   Colour variation in life of Scinax onca sp. n. from the Purus-Madeira Interfluve, Brazilian Amazonia.
 A–B INPA-H 34584 (holotype), adult male from the kilometre 350 of the BR-319 highway, State of Amazonas
 C–D INPA-H 34591, adult female from municipality of Porto Velho, State of Rondônia
E–F INPA-H 26625, adult female from the Floresta Estadual Tapauá Reserve, municipality of Tapauá, State of Amazonas.

Photographs A–D and F were taken after transport of the specimens to the camp, while the image of E was taken immediately in the field.

Scinax onca sp. n.

Diagnosis: A medium-sized species of Scinax characterized by the following combination of characters: (1) SVL 31.3−34.5 mm (n = 13) in males and 35.5−40.4 mm (n = 4) in females; (2) snout truncate in dorsal view, bluntly rounded in lateral view; (3) tarsal tubercles absent; (4) tubercles on lower jaw and knee absent; (5) skin on dorsum shagreen; (6) dentigerous processes of vomers triangular; (7) in life, ground colour of dorsum light brown with dark brown spots and markings; dorsolateral stripes or X-shaped blotch on dorsum absent; flanks light brown with or without dark brown spots; axillar region and groin white with black irregular spots; anterior and posterior surfaces of thighs black (usually bordered by an irregular white streak); webbing between toes black; belly white to yellow, with round dark brown spots; iris bright orange; (8) advertisement call consisting of a single pulsed note; note duration 102−121 ms; 16−18 pulses/note; dominant frequency 1572−1594 Hz; (9) tadpoles with body triangular in lateral view; labial tooth row formula 2(2)/3(1); labial arm absent.

Etymology: The specific name onca refers to the Brazilian common name for the jaguar Pantera onca (Linnaeus, 1758) due the blotchy colour pattern of the new species. Furthermore, the specific name is a reference to frequent encounters of P. onca during the fieldwork in the PMI. The name is used as a noun in apposition.

Distribution and ecology: Scinax onca sp. n. is an exclusive forest dweller, known from two small areas located in the middle section of the PMI (State of Amazonas, Brazil), and two small areas lying in southern part of PMI, close to municipality of Porto Velho (Rondônia, Brazil). The maximum straight distance between the localities is around 500 km (Fig. 1). The middle PMI is covered by tropical lowland rainforest characterized by closed canopy with emergent trees whereas the southern part has a more open lowland rainforest formation with frequent palm trees.

The new species is an explosive breeder. All specimens were encountered after (or during) heavy rains when aggregated at middle-sized or large temporary forest ponds. The ponds were not connected to streams. The males were calling from shrubs growing in or next to the water. Calling males adopted both horizontal and vertical positions on leaves and shrub trunks ca. 50–200 cm above the ground. Other tree frogs found in sympatry with S. onca sp. n. included Dendropsophus leucophyllatus (Beireis, 1783), D. marmoratus (Laurenti, 1768), D. minutus (Peters, 1872), D. parviceps (Boulenger, 1882), D. rhodopeplus (Boulenger, 1882), D. sarayacuensis (Shreve, 1935), Phyllomedusa vaillantii Boulenger, 1882, and Scinax sp. 7 (sensu Ferrão et al. 2016).

Miquéias Ferrão, Jiří Moravec, Rafael de Fraga, Alexandre Pinheiro de Almeida, Igor Luis Kaefer and Albertina Pimentel Lima. 2017. A New Species of Scinax from the Purus-Madeira interfluve, Brazilian Amazonia (Anura, Hylidae). ZooKeys. 706; 137-162.  DOI: 10.3897/zookeys.706.14691


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